The main difficulty encountered by golfers is the development of a swing that will not vary during play because the various muscular movements required are so pattern coordinated through practice that the whole movement (swing) becomes comfortably simple and natural, (much as walking becomes a simple natural movement after it has been learned and practiced). It has been previously believed that a golf club should be swung in an arc which is substantially planar, although the radius of the arc may vary from beginning to end of swing. I have determined that it is more important that the arc should retain its relationship to the so-called "plane" of the swing, than that the radius should remain unchanged, and my studies have indicated that there is some advantage in allowing the radius of curvature of golf club swing to both increase and decrease during the club swing, especially as the club nears the end of its swing, and further, that there should be some deviation from a geometric planar movement. This pattern of movement should be consistent with the user's body muscular limitations to achieve the required maximum power and efficiency.
Various devices have been proposed heretofore which are useful in restricting and guiding the movement of a golf club when swung, but some of the previously proposed devices have made use of ancillary equipment attached to a golf club shaft, or harnesses strapped to the body. These devices interfere considerably with the smooth rhythmic flow of body and club movement and thus detract from the body's senses, and the all important "feel" of the golf swing so vital to the golfer when actually producing the swing when not attached to these devices. In fact the body senses set up a familiarity of acceptance to these interferences to the "feel", so that when the golfer is detached from any of these devices and thus this interference is removed, the body's natural senses become confused and become interferences in themselves by causing change of "feel" and thus a feeling of awkwardness or disharmony during the swing. The result is the golfer is left trying to repeat the swing in conditions alien to those experienced during practise while attached to these devices. It will be appreciated by golfers that they become very finely attuned to different clubs, and the main object of this invention is to provide a golf practice device wherein there is a minimum of interference with the "feel".
Another problem in providing a practice device which is suitable for use by different players is that some players move their clubs in patterns approximating planes inclined to the vertical by a greater amount than the planes in which other players move their clubs, and an object of this invention is to provide means whereby this change of plane can be accommodated.